Information disc recorder/reproducer and method for controlling recording/reproducing speed

ABSTRACT

Information about the number of traversed tracks is acquired with a code at a first rotational speed and a second rotational speed in each area provided by dividing one rotation into m (m is a natural number equal to or larger than 1). As to the information about the number of traversed tracks, a difference is calculated between the areas. A value proportionate to the sum of absolute values of the information about the traversed tracks in the areas is used as a vibration detection value proportionate to vibration amplitude.

TECHNICAL FIELD

The present invention relates to an information diskrecording/reproducing device and a method for controlling arecording/reproducing speed thereof whereby a rotational speed limit iscontrolled in order to prevent a vibration caused by mass eccentricityfrom adversely affecting a disk serving as an information recordingmedium.

BACKGROUND ART

Optical disk reproducing devices have remarkably improved inrecording/reproducing speed in recent years. The improvement inrecording/reproducing speed has been achieved by increasing therotational speeds of optical disks.

However, when an optical disk is increased in rotational speed, avibration caused by mass eccentricity of the optical disk adverselyaffects the control of a servo and so on, resulting in inconvenience onthe user of an optical disk reproducing device.

In order to prevent such adverse effect of a vibration caused by a discof large mass eccentricity, when the disk of large mass eccentricity isloaded, an optical disk reproducing device controls the rotary drivingof an optical disk so as to limit the rotational speed of the opticaldisk.

The vibration amplitude caused by the disk is measured during thecontrol. The measurement is a significant technique for preventing theadverse effect of a vibration caused by the disk of large eccentricityin the optical disk reproducing device. Particularly a vibrationdetecting technique using a track count is known as an inexpensivedetecting method not demanding additional cost for the installation of avibration sensor or the like which directly detects a mechanicalvibration.

As described above, the conventional optical disk reproducing devicewhich uses a track count to detect a vibration will be described below.An optical disk reproducing device of Japanese Patent Laid-Open No.2000-113581 will be discussed as an example.

FIG. 9 is a block diagram showing the configuration of a conventionaloptical disk reproducing device for detecting a vibration using a trackcount. In FIG. 9, reference numeral 900 denotes an optical diskreproducing device, reference numeral 801 denotes a base, referencenumeral 802 denotes a disk motor fixed on the base 801, referencenumeral 803 denotes insulators for supporting the base 801, referencenumeral 804 denotes a disk to be reproduced that is mounted on the diskmotor 802, reference numeral 901 denotes an optical head, referencenumeral 902 denotes an elastic member for suspending the optical head901 from the base 801, reference numeral 903 denotes a light beam whichis incident on the optical disk 804 from the optical head 901, referencenumeral 904 denotes information recording tracks which are formed likeconcentric circles or spirals with constant pitches on an informationrecording surface 804A of the disk 804, reference numeral 905 denotes atrack cross detecting section which generates a track cross pulse and across signal from a signal reproduced when the light beam 903 traversesthe information recording tracks 904, reference numeral 906 denotes acounting section for counting the track cross pulses, reference numeral907 denotes a measuring section for deciding a quantity of masseccentricity based on the counting result of the counting section 906,and reference numeral 908 denotes a motor control section which controlsthe number of rotations of the disk motor 802 and outputs rotation angleinformation to the measuring section 907.

Regarding the conventional optical disk reproducing device configuredthus, a vibration detecting operation will be described below.

First, in the optical disk reproducing device 900, the optical head 901is kept at a fixed distance from the disk 804 so that the focus of theoptical beam 903 is positioned on the information recording surface 804Aof the disk 804. The relative position of the optical head 901 to thedisk 804 in the radius direction (the direction of arrow R) of the disk804 has a vibration characteristic indicated by a natural frequency foA,which is determined by the mass of optical head 901 and the springconstant of the elastic member 902 made of a material such as a metal, aresin, and a rubber.

The base 801 is supported by the insulators 803 made of a material suchas a metal, a resin, and a rubber. When centrifugal force generated bythe rotation of the disk 804 is propagated to the base 801 through thedisk motor 802, the base 801 is vibrated according to a characteristicindicated by a natural frequency foM, which is determined by the springconstant of the insulators 803 and the mass of all the constituentelements including the base 801, the optical head 901, the disk motor802, and the disk 804 that are mounted on the base 801.

The motor control section 908 rotates the disk motor 802 at a first rpm(low-speed rotation) sufficiently lower than the natural frequency foA.The optical disk 804 mounted on the disk motor 802 rotates at the firstrpm.

At the first rpm sufficiently lower than the natural frequency foA, theoptical head 901 is vibrated integrally with the base 801. The relativepositions of the optical head 901 and the optical disk 804 hardlychange. Hence, at the first rpm sufficiently lower than the naturalfrequency foA, the light beam 903 traverses the information tracks 904.The number of the information recording tracks 904 corresponds to aneccentricity amount thereof. The light beam 903 generates a track crosscorresponding to the number of the information recording tracks 904.

Based on the reproduction signal of the optical head 901, the trackcross detecting section 905 detects the track cross corresponding to thenumber of the information recording tracks 905 traversed by the lightbeam 903. The track cross detecting section 905 generates a track crosspulse corresponding to the detected track cross. The track crossdetection section 905 outputs the generated track cross pulse to thecounting section 906.

The counting section 906 counts track cross pulses of one rotation ofthe disk 804 based on rotation angle information from the motor controlsection 908. The measuring section 907 stores, as N1(0) to N1 (n−1), thecounting result of track cross pulses of one rotation of the disk 804which is counted by the counting section 906 for each area obtained bydividing one rotation into n.

Subsequently, the motor control section 908 rotates the disk motor 802at a second rpm (high-speed rotation) which is higher than the naturalfrequency foA and is lower than the natural frequency foM. The masseccentricity of the disk 804 generates centrifugal force on the disk804. The base 801 is vibrated according to amplitude determined by thespring constant of the insulators 803, the mass eccentricity amount ofthe disk 804, the mass of all the constituent elements mounted on thebase 801.

When the disk motor 802 is rotated at the second rpm which is higherthan the natural frequency foA and lower than the natural frequency foM,only the base 801, the disk motor 802, and the disk 804 are integrallyvibrated and the optical head 901 is made stationary. Hence, a relativedisplacement between the disk 804 and the optical head 901 is equal tothe vibration displacement of the base 801. As a result, the light beam903 generates a track cross having the number of tracks corresponding tothe sum of the eccentricity amount of the information recording track904 and the vibration amplitude of the base 801.

Based on the reproduction signal of the optical head 901, the trackcross detecting section 905 detects a track cross corresponding to thenumber of tracks which are equivalent to the sum of the eccentricityamount of the information recording track 904 and the vibrationamplitude of the base 801. The track cross detecting section 905generates a track cross pulse corresponding to the number of trackswhich are equivalent to the sum of the eccentricity amount of theinformation recording track 904 and the vibration amplitude of the base801. The track cross detecting section 905 outputs generated track crosspulse to the counting section 906.

The counting section 906 counts a track cross pulse of one rotation ofthe disk 804 based on rotation angle information from the motor controlsection 908. The measuring section 907 performs an operation to obtainthe vibration amplitude of the base 801 after subtracting count resultsN1(1) to N1(n) from count results N2(1) to N2(n) counted by themeasuring section 906.

To be specific, the vibration amplitude is obtained by the equationbelow. $\begin{matrix}\begin{matrix}{{{dat}\quad\lbrack 1\rbrack} = {{{N1}(1)} - {{N2}(1)}}} \\{{{dat}\quad\lbrack 2\rbrack} = {{{N1}(2)} - {{N2}(2)}}} \\\vdots \\{{{dat}\quad\lbrack n\rbrack} = {{{N1}(n)} - {{N2}(n)}}}\end{matrix} & ( {{Equation}\quad 15} )\end{matrix}$

For example, when n=6, the following equations are established:$\begin{matrix}{{{VIBRATIN}\quad{AMPLITUDE}\quad{1\lbrack n\rbrack}} = \frac{2}{\sqrt{3}}} & ( {{Equation}\quad 16} ) \\\sqrt{{{{DAT}\lbrack n\rbrack}^{2} + {{{DAT}\lbrack n\rbrack}{{DAT}\lbrack {n + 1} \rbrack}} + {{DAT}\lbrack {n + 1} \rbrack}^{2}}} & \quad \\{{{VIBRATION}\quad{AMPLITUDE}\quad{2\quad\lbrack n\rbrack}} = \frac{2}{\sqrt{3}}} & ( {{Equation}\quad 17} ) \\\sqrt{{{{DAT}\lbrack n\rbrack}^{2} + {{{DAT}\lbrack n\rbrack}{{DAT}\lbrack {n + 2} \rbrack}} + {{DAT}\lbrack {n + 2} \rbrack}^{2}}} & \quad\end{matrix}$(when n=1 to 6 and n>6, n=n−6 is established)

In an operation of a square root, since the number of program steps isordinarily increased, a value proportionate to the square of vibrationamplitude is used as a vibration detection value. Further, of trackcount data in an area divided into n, a vibration detection value isfound only from data in two areas. Thus, an error count of one areaseriously affects a detection value. In order to avoid the influence,the following method is known: 12 vibration detection values in totalare calculated by (equation 16) and (equation 17), from which six valuesare calculated, respectively, and an average value of these pluralmedian values or the twelve pieces of data is used as a vibrationdetection value.

Then, the maximum rotational speed of a disk of an optical disk deviceis determined by comparing the calculated vibration detection value witha threshold value.

However, in the conventional optical disk reproducing device disclosedin Japanese Patent Laid-Open No. 2000-113581, the track count result ofan eccentric component measured at the first rotational speed issubtracted by arithmetic after the track count result is measured at thesecond rotational speed. Thereafter, it is necessary to further performa complicated operation to obtain a vibration detection valuecorresponding to vibration amplitude. Thus, a value proportionate to thesquare of vibration amplitude is usually used as a vibration detectionvalue. In this case, since the square of vibration amplitude is used, itis necessary to use a high-precision variable (with a large significantfigure) for calculation in order to precisely control arecording/reproducing speed.

Moreover, a number of multiplications are used and the calculation iscomplicated, thereby increasing the number of program steps for control.For this reason, it takes a long time to calculate a vibration detectionvalue, delaying the result. Thus, it is not possible to promptly controla recording/reproducing speed.

Therefore, it is an object of the present invention to provide aninformation disk recording/reproducing device and a method forcontrolling a recording/reproducing speed thereof whereby arecording/reproducing speed can be precisely controlled without thenecessity for using a high-precision variable for computing a vibrationdetection value, and a vibration detection value can be promptlycalculated and a recording/reproducing speed can be controlled withoutthe necessity for an extra number of program steps.

DISCLOSURE OF INVENTION

An information disk recording/reproducing device according to claim 1 ofthe present invention, in which recording or reproduction can beperformed on an information disk having an information recording trackformed like a spiral or a concentric circle, comprises: a disk rotatingunit for rotating the information disk; a rotational positioninformation output unit for outputting rotational position informationfor the information disk of the disk rotating unit in each area providedby dividing one rotation into m (m is a natural number equal to orlarger than 2); a reading unit for reading an information signal fromthe information disk; a radius direction driving unit for driving thereading unit in the radius direction of the information disk; a trackcross detecting unit for detecting a track cross caused by crossing andgenerating a track cross signal based on a reproduction signal when thereading unit is traversed on the information recording track by thedriving of the radius direction driving unit; a track cross directiondetecting unit for detecting the direction of the track cross caused bythe crossing based on the reproduction signal when the reading unit istraversed on the information recording track by the driving of theradius direction driving unit; a counting unit for counting the pulsesof a track cross signal from the track cross detecting unit, with a codeindicating a track cross direction from the track cross directiondetecting unit, based on the output from the rotational positioninformation output unit in each of the areas divided into m; and acontrol unit which rotates the disk rotating unit at a first speed,obtains a first counted value of the counting unit while making theradius direction driving unit nonoperational, rotates the disk rotatingunit at one or more kinds of rotational speeds of second, third, . . .rotational speeds higher than the first rotational speed, obtainssecond, third, . . . counted values of the counting unit while makingthe radius direction driving unit nonoperational, and compares adifference between the first counted value and the second, third, . . .counted values with a threshold value so as to determine the maximumrotational speed of the information disk, the threshold value beingpredetermined while using, as a vibration detection value, a valueproportionate to the sum of absolute values of counted values obtainedin the areas divided into m.

With the configuration of the information disk recording/reproducingdevice, it is possible to calculate a vibration detection valueproportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout an extra number of program steps.

An information disk recording/reproducing device according to claim 2 ofthe present invention, in which recording or reproduction can beperformed on an information disk having an information recording trackformed like a spiral or a concentric circle, comprises: a disk rotatingunit for rotating the information disk; a rotational positioninformation output unit for outputting rotational position informationfor the information disk of the disk rotating unit in each area providedby dividing one rotation into n (n is a natural number equal to orlarger than 2); a rotational position information dividing unit whichfurther divides into k (k is a natural number equal to or larger than 1)the area having been provided by dividing one rotation into n for therotational position information from the rotational position informationoutput unit and outputs the rotational position information in each ofm=n·k areas; a reading unit for reading an information signal from theinformation disk; a radius direction driving unit for driving thereading unit in the radius direction of the information disk; a trackcross detecting unit for detecting a track cross caused by crossing andgenerating a track cross signal based on a reproduction signal when thereading unit is traversed on the information recording track by thedriving of the radius direction driving unit; a track cross directiondetecting unit for detecting the direction of the track cross caused bythe crossing on the reproduction signal when the reading unit istraversed on the information recording track by the driving of theradius direction driving unit; a counting unit for counting the pulsesof a track cross signal from the track cross detecting unit, with a codeindicating a track cross direction from the track cross directiondetecting unit, based on the output from the rotational positioninformation dividing unit in each of the areas divided into m; and acontrol unit which rotates the disk rotating unit at a first speed,obtains a first counted value of the counting unit while making theradius direction driving unit nonoperational, rotates the disk rotatingunit at one or more kinds of rotating speeds of second, third, . . .rotational speeds higher than the first rotational speed, obtainssecond, third, . . . counted values of the counting unit while makingthe radius direction driving unit nonoperational, and compares adifference between the first counted value and the second, third, . . .counted values with a predetermined threshold value so as to determinethe maximum rotational speed of the information disk while using, as avibration detection value, a value proportionate to the sum of absolutevalues of counted values obtained in the areas divided into m.

With this configuration of the information disk recording/reproducingdevice, the number of traversed tracks is counted for each of the kareas obtained by further evenly dividing the rotational positioninformation of the rotational position information detecting unit. Thus,it is possible to acquire more detailed rotational position informationfor one rotation, increase accuracy, and calculate a vibration detectionvalue proportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout an extra number of program steps.

Moreover, an information disk recording/reproducing device according toclaim 3 of the present invention is the information diskrecording/reproducing device according claim 1 or 2. In each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 18)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 19} )\end{matrix}$and a value proportionate to the vibration quantity is used as avibration detection value.

With this configuration of the information disk recording/reproducingdevice, it is possible to calculate a vibration detection valueproportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout an extra number of program steps.

Further, an information disk recording/reproducing device according toclaim 4 of the present invention is the information diskrecording/reproducing device according claim 1 or 2. In each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 20)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 21} )\end{matrix}$a value proportionate to the vibration quantity is used as a vibrationdetection value, and the m divisions for one rotation is determinedwithin a permissible error range based on the maximum value of an errorrelative to an actual vibration quantity at this point, the maximumvalue being expressed by the equation below: $\begin{matrix}{{ERROR} \leq {1 - {\cos\frac{\pi}{m}}}} & ( {{Equation}\quad 22} )\end{matrix}$

With this configuration of the information disk recording/reproducingdevice, since an optimum number of divisions for one rotation isdetermined so that the error range of a vibration detection value iswithin a required range, it is possible to calculate, with requiredaccuracy, a vibration detection value proportionate to vibrationamplitude without the necessity for complicated calculations. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without an extra number of programsteps.

Further, an information disk recording/reproducing device according toclaim 5 of the present invention is the information diskrecording/reproducing device according to claim 1 or 2. In each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 23)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 24} )\end{matrix}$a value proportionate to the vibration quantity is used as a vibrationdetection value, and the m divisions for one rotation is set at 24 sothat an error relative to an actual vibration quantity at this point hasa maximum value of 1% or less.

With this configuration of the information disk recording/reproducingdevice, it is possible to keep an error of a calculated vibrationquantity value with required accuracy while minimizing the number ofdivisions of the rotational position information output unit. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without the necessity for an extranumber of program steps.

Further, a method for controlling a recording/reproducing speed of aninformation disk recording/reproducing device according to claim 6 ofthe present invention, in which recording or reproduction can beperformed on an information disk having an information recording trackformed like a spiral or a concentric circle, the device comprising adisk rotating unit for rotating the information disk, a reading unit forreading an information signal from the information disk, and a radiusdirection driving unit for driving the reading unit in the radiusdirection of the information disk. This method comprises the steps of:rotating the information disk; outputting rotational positioninformation for the information disk in each area provided by dividingone rotation into m (m is a natural number equal to or larger than 2);reading an information signal from the information disk; driving thereading unit in the radius direction of the information disk; detectinga track cross caused by crossing and generating a track cross signalbased on a reproduction signal when the reading unit is traversed on theinformation recording track by the driving of the radius directiondriving unit; detecting the direction of the track cross caused by thecrossing based on the reproduction signal when the reading unit istraversed on the information recording track by the driving of theradius direction driving unit; counting the pulses of a track crosssignal, with a code indicating the track cross direction, to obtain afirst counted value in each of the areas provided by dividing onerotation of the rotational position information into m while rotatingthe disk rotating unit at a first speed and making the radius directiondriving unit nonoperational; counting the pulses of the track crosssignal, with the code indicating the track cross direction, to obtainsecond, third, counted values in each of the areas provided by dividingone rotation of the rotational position information into m whilerotating the disk rotating unit at one or more kinds of second, third, .. . rotational speeds higher than the first rotational speed and makingthe radius direction driving unit nonoperational; and comparing adifference between the first counted value and the second, third, . . .counted values with a predetermined threshold value so as to determinethe maximum rotational speed of the information disk while using, as avibration detection value, a value proportionate to the sum of absolutevalues of counted values obtained in the areas divided into m.

According to the method for controlling a recording/reproducing speed ofthe information disk recording/reproducing device, it is possible tocalculate a vibration detection value proportionate to vibrationamplitude without the necessity for complicated calculations. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without the necessity for an extranumber of program steps.

A method for controlling a recording/reproducing speed of an informationdisk recording/reproducing device according to claim 7 of the presentinvention, in which recording or reproduction can be performed on aninformation disk having an information recording track formed like aspiral or a concentric circle, the device comprising a disk rotatingunit for rotating the information disk, a reading unit for reading aninformation signal from the information disk, and a radius directiondriving unit for driving the reading unit in the radius direction of theinformation disk. This method comprises the steps of: rotating theinformation disk; outputting rotational position information for theinformation disk in each of m=n·k areas provided by further dividinginto k (k is a natural number equal to or larger than 1) an area havingbeen provided by dividing one rotation into m (m is a natural numberequal to or larger than 2); reading an information signal from theinformation disk; driving the reading unit in the radius direction ofthe information disk; detecting a track cross caused by crossing andgenerating a track cross signal based on a reproduction signal when thereading unit is traversed on the information recording track by thedriving of the radius direction driving unit; detecting the direction ofthe track cross caused by the crossing based on the reproduction signalwhen the reading unit is traversed on the information recording track bythe driving-of the radius direction driving unit; counting the pulses ofa track cross signal, with a code indicating the track cross direction,to obtain a first counted value in each of the areas provided bydividing one rotation of the rotational position information into mwhile rotating the disk rotating unit at a first speed and making theradius direction driving unit nonoperational; counting the pulses of thetrack cross signal, with the code indicating the track cross direction,to obtain second, third, . . . counted values in each of the areasprovided by dividing one rotation of the rotational position informationinto m while rotating the disk rotating unit at one or more kinds ofsecond, third, . . . rotational speeds higher than the first rotationalspeed and making the radius direction driving unit nonoperational; andcomparing a difference between the first counted value and the second,third, . . . counted values with a predetermined threshold value so asto determine the maximum rotational speed of the information disk whileusing, as a vibration detection value, a value proportionate to the sumof absolute values of counted values obtained in the areas divided intom.

According to the method for controlling a recording/reproducing speed ofthe information disk recording/reproducing device, the number oftraversed tracks is counted for each of the k areas obtained by furtherevenly dividing the rotational position information of the rotationalposition information detecting unit. Thus, it is possible to acquiremore detailed rotational position information for one rotation, increaseaccuracy, and calculate a vibration detection value proportionate tovibration amplitude without the necessity for complicated calculations.Hence, it is possible to promptly calculate a vibration detection valueand control a recording/reproducing speed without an extra number ofprogram steps.

A method for controlling a recording/reproducing speed of an informationdisk recording/reproducing device according to claim 8 of the presentinvention is the method for controlling a recording/reproducing speed ofthe information disk recording/reproducing device according claim 6 or7. In each of the areas divided into m, a difference between the countedvalue at the first rotational speed and the counted value at each of thesecond, third, . . . rotational speeds is expressed by the equationbelow:DAT[1]˜DAT[m]  (Equation 25)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 26} )\end{matrix}$and a value proportionate to the vibration quantity is used as avibration detection value.

According to the method for controlling a recording/reproducing speed ofthe information disk recording/reproducing device, it is possible tocalculate a vibration detection value proportionate to vibrationamplitude without the necessity for complicated calculations. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without an extra number of programsteps.

Further, a method for controlling a recording/reproducing speed of aninformation disk recording/reproducing device according to claim 9 ofthe present invention is the method for controlling arecording/reproducing speed of the information diskrecording/reproducing device according claim 6 or 7. In each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 27)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 28} )\end{matrix}$a value proportionate to the vibration quantity is used as a vibrationdetection value, and the m divisions for one rotation is determinedwithin a permissible error range based on the maximum value of an errorrelative to an actual vibration quantity at this point, the maximumvalue being expressed by the equation below: $\begin{matrix}{{ERROR} \leq {1 - {\cos\frac{\pi}{m}}}} & ( {{Equation}\quad 29} )\end{matrix}$

According to the method of controlling a recording/reproducing speed ofthe information disk recording/reproducing device, since an optimumnumber of divisions for one rotation is determined so that the errorrange of a vibration detection value is within a required range, it ispossible to calculate, with required accuracy, a vibration detectionvalue proportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout an extra number of program steps.

Moreover, a method for controlling a recording/reproducing speed of aninformation disk recording/reproducing device according to claim 10 ofthe present invention is the method for controlling arecording/reproducing speed of the information diskrecording/reproducing device according claim 6 or 7. In each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 30)a vibration quantity at this point is approximated by the equationbelow: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 31} )\end{matrix}$a value proportionate to the vibration quantity is used as a vibrationdetection value, and the m divisions for one rotation is set at 24 sothat an error relative to an actual vibration quantity at this point hasa maximum value of 1% or less.

According to the method for controlling a recording/reproducing speed ofthe information disk recording/reproducing device, it is possible tokeep an error of a calculated vibration quantity value with requiredaccuracy while minimizing the number of divisions of the rotationalposition information output unit. Hence, it is possible to promptlycalculate a vibration detection value and control arecording/reproducing speed without the necessity for an extra number ofprogram steps.

As described above, it is possible to calculate a vibration detectionvalue proportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout the necessity for an extra number of program steps.

In addition, the number of traversed tracks is counted for each of the kareas obtained by further evenly dividing the rotational positioninformation of the rotational position information detecting unit. Thus,it is possible to acquire more detailed rotational position informationfor one rotation, increase accuracy, and calculate a vibration detectionvalue proportionate to vibration amplitude without the necessity forcomplicated calculations. Hence, it is possible to promptly calculate avibration detection value and control a recording/reproducing speedwithout the necessity for an extra number of program steps.

Further, since an optimum number of divisions for one rotation isdetermined so that the error range of a vibration detection value iswithin a required range, it is possible to calculate, with requiredaccuracy, a vibration detection value proportionate to vibrationamplitude without the necessity for complicated calculations. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without the necessity for an extranumber of program steps.

Furthermore, it is possible to keep an error of a calculated vibrationquantity value with required accuracy while minimizing the number ofdivisions of the rotational position information output unit. Hence, itis possible to promptly calculate a vibration detection value andcontrol a recording/reproducing speed without the necessity for an extranumber of program steps.

Therefore, a recording/reproducing speed can be precisely controlledwithout the necessity for using a high-precision variable for computinga vibration detection value, and a vibration detection value can bepromptly calculated and a recording/reproducing speed can be controlledwithout the necessity for an extra number of program steps.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of an informationdisk recording/reproducing device according to Embodiment 1 of thepresent invention;

FIG. 2 is an explanatory drawing showing an operating state when a diskis rotated at low speed in the information disk recording/reproducingdevice according to Embodiment 1;

FIG. 3 is an explanatory drawing showing an operating state when thedisk is rotated at high speed in the information diskrecording/reproducing device according to Embodiment 1;

FIG. 4 is an explanatory drawing showing a vibration component caused byeccentricity of the disk in the information disk recording/reproducingdevice according to Embodiment 1;

FIG. 5 is a block diagram showing the configuration of an informationdisk recording/reproducing device according to Embodiment 2 of thepresent invention;

FIG. 6 is an explanatory drawing showing a vibration component caused byeccentricity of the disk in the information disk recording/reproducingdevice according to Embodiment 2;

FIG. 7 is an explanatory drawing showing a difference of counted valuesbetween the presence and absence of the detection of a track crossdirection in the information disk recording/reproducing device accordingto Embodiment 2;

FIG. 8 is an explanatory drawing showing a method of calculating avibration quantity error with the detection of a track cross directionof the disk in the information disk recording/reproducing deviceaccording to Embodiment 2; and

FIG. 9 is a block diagram showing the configuration of a conventionalinformation disk recording/reproducing device.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the accompanying drawings, the following willspecifically describe an information disk recording/reproducing deviceand a method for controlling a recording/reproducing speed thereof thatrepresent embodiments of the present invention.

Embodiment 1

Referring to FIGS. 1 to 4, the following will describe an informationdisk recording/reproducing device and a method for controlling arecording/reproducing speed thereof according to Embodiment 1. A DVD-ROMreproducing device will be discussed as an example.

FIG. 1 is a block diagram showing the configuration of the DVD-ROMreproducing device serving as an example of the information diskrecording/reproducing device according to Embodiment 1. FIG. 2 is anexplanatory drawing showing a relationship between a disk rotation angleand a rotational position information signal, a track cross signal, anda track relative position when a track cross caused by eccentricity ismeasured at a first rotational speed (low-speed rotation) according toEmbodiment 1. FIG. 3 is an explanatory drawing showing a relationshipbetween a disk rotation angle and a rotational position informationsignal, a track cross signal, and a track relative position when a trackcross caused by eccentricity+vibration is measured at second, third, . .. rotational speeds (high-speed rotation) higher than the firstrotational speed according to Embodiment 1. FIG. 4 is an explanatorydrawing showing a method for calculating a track cross caused by avibration based on the measurement results of a track cross caused byeccentricity at the first speed and the measurement results of a trackcross caused by eccentricity+vibration at the second, third, . . .rotational speeds higher than the first rotational speed.

In FIG. 1, a DVD-ROM reproducing device 101 can reproduce a variety ofoptical disks 102. The DVD-ROM reproducing device 101 described in thepresent embodiment can reproduce, for example, disks of CD-ROM (CD-ROM,CD-R, and CD-RW), DVD-ROM (DVD-5, DVD-9, DVD-R4.7G), and DVD-R3.9G.

Reference numeral 103 denotes a disk rotating unit which rotates theoptical disk 102 loaded in the DVD-ROM reproducing device 101 at apredetermined speed. Reference numeral 104 denotes a reading unit whichreads an information signal from the optical disk 102. The reading unit104 is constituted of, for example, a laser light-emitting element 105having two different oscillation wavelengths for a CD-ROM and a DVD-ROM,an objective lens 106 for gathering laser light, and a light detectingelement 107 having two systems for a CD-ROM and a DVD-ROM in the DVD-ROMdevice. The output of the light detecting element 107 is amplified, anoutput signal from the light detecting element 107 is selected accordingto the kind of the optical disk 102, and a tracking error signal (TE), afocus error signal (FE), a reproduction signal (RF), an All Sum signal(AS), an RF envelope signal (RFENV) and so on are generated based on theoutput signal, and the signals are outputted. Reference numeral 108denotes a converting unit which converts a reproduction signal outputtedfrom the reading unit 104 to digital data.

Reference numeral 109 denotes a radius direction driving unit whichdrives the reading unit 104 in the radius direction of the optical disk102. The radius direction driving unit 109 is constituted of, forexample, a traverse driving unit 110 which moves the whole reading unit104 in the radius direction of the optical disk and a tracking actuator111 which drives the object lens 106 in the reading unit 104 in theradius direction and finely drives the object lens 106 in the radiusdirection of the optical disk 102.

Reference numeral 112 denotes a track cross detecting unit whichgenerates a track cross pulse based on a reproduction signal when thelaser light of the reading unit 104 traverses tracks on the opticaldisk.

Reference numeral 113 denotes a track cross direction detecting unitwhich detects a direction when the laser light of the reading unit 104traverses the tracks on the optical disk. For example, the track crossdetecting unit 112 and the track cross direction detecting unit 113binarize a tracking error signal, which is outputted from the readingunit 104, by using a hysteresis comparator, a comparator, or the likeand generate a track count signal TKC. Further, a non-on-track signalOFTR is similarly generated from the envelope of an RF signal and atrack cross direction signal is generated based on a phase relationshipbetween TKC and OFTR signals. A method of directly using the TKC and amethod of latching the TKC by OFTR to generate a detected pulse, andother methods are available for a track cross detected pulse.

Reference numeral 114 denotes a rotational position information outputunit which detects a rotation angle of the disk rotating unit 103. Therotational position information output unit 114 generally uses a signalcalled an FG pulse which is generated from, for example, the output of aHall device of a disk motor. As to the FG signal, three pulses areoutputted for one rotation in a three-phase motor. Thus, a rotationangle can be detected in 60 degrees by counting both of a rising edgeand a falling edge. Moreover, other than the FG pulse, the followingmethod is available: a rotational speed detecting unit using an encoderis added to the disk motor and a rotational speed is detected with anarbitrary resolution.

Reference numeral 115 denotes a counting unit which has a mode forcounting the number of track crossing times with a code indicating adirection based on the outputs of the track cross detecting unit 112 andthe track cross direction detecting unit 113 according to the output ofthe rotational position information output unit 114, and a mode forperforming counting without a code indicating a track cross direction.When a rotation angle can be detected every 60 degrees as describedabove, one rotation is divided into six areas and the number of trackcounts is counted with or without the code for each of the areas.

Reference numeral 116 denotes a control unit which receives signals fromthe converting unit 108 and the counting unit 115, processes thesignals, and controls the disk rotating unit 103, the reading unit 104,the converting unit 108, and the radius direction driving unit 109.

Subsequently, the following will describe the operation of the controlunit 116 which detects a vibration and sets the maximum rotationalspeed.

The present embodiment will describe an example in which the DVD-ROMreproducing device 101 has corresponding reproducing speeds of:

-   CD:    -   8×CAV (about 1660 rpm)    -   16×CAV (about 3330 rpm)    -   24×CAV (about 4990 rpm)-   DVD:    -   2.5×CAV (about 1430 rpm)    -   5×CAV (about 2870 rpm)    -   8×CAV (about 4590 rpm)

The control unit 116 controls the disk rotating unit 103 to make arotation at the first rotational speed. It is preferable that the firstrotational speed is a sufficiently low speed causing no vibration whenthe information disk 102 is rotated. For example, in the presentembodiment, measurements are performed at the first rotational speed ofCD 8×CAV (1660 rpm) and DVD 2.5×CAV (1430 rpm).

Then, the radius direction driving unit 109 is made nonoperational.Track crossing is caused by an eccentric component between the tracks ofthe information disk 102 and the reading unit 104. Thus, for each areaprovided by dividing one rotation into m (m is a natural number equal toor larger than 2), the counted value of the counting unit 115 isobtained with the code indicating a track cross direction based on theoutput of the rotational position information output unit 114.

Since rotational position information is normally detected using the FGpulse of a spindle motor, m is determined according to the number ofpoles of the motor. In the case of three poles, the area is divided intosix at a rising edge and a falling edge. In the case of four poles, thearea is similarly divided into eight. Of course, the plurality ofdivided areas may be regarded as one area to obtain a counted value witha smaller number of areas, or one area may be time-divided to obtain acounted value with a larger number of areas.

The present embodiment will describe an example of dividing one rotationinto six areas to obtain a counted value by using a spindle motor withthree poles.

Counted value data obtained at the first rotational speed is expressedby the equation below.DAT1[1]˜DAT1[6]  (Equation 32)

FIG. 2 shows a relationship between a disk rotation angle and arotational position information signal, a track cross signal, and atrack relative position.

Further, measurements are performed at the second, third, . . . speedshigher than the first speed. The present embodiment will describe anexample of measurements only at the second rotational speed higher thanthe first rotational speed.

Also in the step of obtaining a counted value of the counting unit 115when a rotation is made at the second speed higher than the first speed,the counting results of the number of track crossing times can beobtained at a rotation angle of 60 degrees as in the step of obtainingthe counting results of the counting unit 115 when a rotation is made atthe first speed. In the present embodiment, a counted value is obtainedat a common rotational speed of 4000 rpm in order to decide whether ornot reproduction can be performed at the maximum speed (CD 24×CAV, DVD8×CAV) both on a DVD-ROM and a CD-ROM.

The control unit 116 controls the disk rotating unit 103 to make arotation at 4000 rpm. Similarly, the radius direction driving unit 109is made nonoperational. Then, track crossing is caused by an eccentriccomponent+a vibration component between the tracks of the informationdisk 102 and the reading unit 104. Thus, the counted value of thecounting unit 115 is obtained with the code indicating a track crossdirection based on the output of the rotational position informationoutput unit 114 for each of the areas obtained by dividing one rotationinto six. The obtained counted value is expressed by the equation below.DAT2[1]˜DAT2[6]  (Equation 33)

FIG. 3 shows a relationship between a disk rotation angle and arotational position information signal, a track cross signal, and atrack relative position.

Therefore, track crossing caused by a vibration is calculated bysubtracting a counted value at the first rotational speed from a countedvalue at the second rotational speed (4000 rpm) at each correspondingrotation angle. FIG. 4 shows the relationship.

The data of each area is expressed by the equation below.DAT[1]=DAT2[1]−DAT1[1]DAT[2]=DAT2[2]−DAT1[2]DAT[3]=DAT2[3]−DAT1[3]DAT[4]=DAT2[4]−DAT1[4]DAT[5]=DAT2[5]−DAT1[5]DAT[6]=DAT2[6]−DAT1[6]  (Equation 34)To be precise, based on the data, vibration amplitude is expressed bythe equations below. $\begin{matrix}{\begin{matrix}{VIBRATIN} \\{{AMPLITUDE}\quad{1\lbrack n\rbrack}}\end{matrix} = \frac{2}{\sqrt{3}}} & ( {{Equation}\quad 35} ) \\{\quad\sqrt{{{{DAT}\lbrack n\rbrack}^{2} + {{{DAT}\lbrack n\rbrack}{{DAT}\lbrack {n + 1} \rbrack}} + {{DAT}\lbrack {n + 1} \rbrack}^{2}}}} & \quad \\{\begin{matrix}{VIBRATION} \\{{AMPLITUDE2}\quad\lbrack n\rbrack}\end{matrix} = \frac{2}{\sqrt{3}}} & ( {{Equation}\quad 36} ) \\{\quad\sqrt{{{{DAT}\lbrack n\rbrack}^{2} - {{{DAT}\lbrack n\rbrack}{{DAT}\lbrack {n + 2} \rbrack}} + {{DAT}\lbrack {n + 2} \rbrack}^{2}}}} & \quad\end{matrix}$(when n=1 to 6 and n>6, n=n−6 is established) In order to prevent anincrease in the number of calculating steps, approximation is performedin a simplified manner by the equation below. $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{6}{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 37} )\end{matrix}$

By comparing a vibration detection value obtained by (equation 37) witha predetermined threshold value, it is decided whether or notreproduction should be performed at the maximum rotational speed. When avibration quantity equal to or larger than the threshold value isdetected, the reproducing speed of a CD is limited up to 16×CAV and thereproducing speed of a DVD is limited up to 5×CAV. When a vibrationquantity equal to or larger than the threshold value is not detected,reproduction can be performed both on a CD and a DVD at the maximumreproducing speed.

As described above, according to Embodiment 1, a vibration detectionvalue proportionate to vibration amplitude can be calculated without thenecessity for complicated calculations. Thus, it is possible to promptlycalculate a vibration detection value and control arecording/reproducing speed without the necessity for an extra number ofprogram steps.

Besides, the present embodiment described the DVD-ROM reproducing deviceas an example. The present embodiment can be similarly carried out in adisk recording/reproducing device such as a CD-ROM reproducing deviceand a CD-R/RW recording/reproducing device.

Further, the present embodiment described the example in which theinformation disk 102 is rotated at CAV (constant rotational speed)during reproduction. Even when the information disk 102 is controlled atCLV (constant linear velocity), ZCLV (constant linear velocity in eachzone), PCAV (combination of CLV and CAV), and so on during recording andreproduction, the present embodiment can be similarly carried out bydeciding whether control is performed so as to have a speed not reachingthe rotational speed for the similar vibration detection or a speedaround the rotational speed, or control is performed so as to rotate theinformation disk 102 to the maximum rotational speed.

Further, the present embodiment described the example in which therotational speed of the information disk 102 is controlled by measuringtrack crossing, caused by eccentricity vibration, only at the secondrotational speed higher than the first rotational speed. The presentembodiment can be similarly carried out by performing measurements atone or more rotational speeds such as the second, third, . . .rotational speeds higher than the first rotational speed and comparing avibration quantity with a threshold value having been prepared for eachof the rotational speeds.

Moreover, the present embodiment described the example in which thespindle motor serving as the disk rotating unit 103 has three poles, therising edge and the falling edge of the FG pulse are used to divide onerotation into six areas, and track crossing is measured for each of theareas. The present embodiment can be similarly carried out when thespindle motor has four poles and one rotation is divided into eightareas and when the one rotation is divided into more areas.

Embodiment 2

Referring to FIGS. 5 to 7, the following will describe an informationdisk recording/reproducing device and a method for controlling arecording/reproducing speed thereof according to Embodiment 2. A DVD-ROMreproducing device will be discussed as an example.

FIG. 5 is a block diagram showing the configuration of the DVD-ROMreproducing device serving as an example of the information diskrecording/reproducing device according to Embodiment 2. FIG. 6 is anexplanatory drawing showing a method for calculating track crossingcaused by a vibration based on the measurement results of track crossingcaused by eccentricity at a first rotational speed (low-speed rotation)and the measurement results of track crossing caused byeccentricity+vibration at second, third, . . . , rotational speeds(high-speed rotation) higher than the first rotational speed accordingto Embodiment 2. FIG. 7 is an explanatory drawing showing a differenceof counted values between the presence and absence of the detection of atrack cross direction according to Embodiment 2.

In FIG. 5, a DVD-ROM reproducing device 101 can reproduce a variety ofoptical disks 102. The DVD-ROM reproducing device 101 described in thepresent embodiment can reproduce, for example, disks of CD-ROM (CD-ROM,CD-R, and CD-RW), DVD-ROM (DVD-5, DVD-9, DVD-R4.7G), and DVD-R3.9G.

Reference numeral 103 denotes a disk rotating unit which rotates theoptical disk 102 loaded in the DVD-ROM reproducing device 101 at apredetermined speed. Reference numeral 104 denotes a reading unit whichreads an information signal from the optical disk 102. The reading unit104 is constituted of, for example, a laser light-emitting element 105having two different oscillation wavelengths for a CD-ROM and a DVD-ROM,an objective lens 106 for gathering laser light, and a light detectingelement 107 having two systems for a CD-ROM and a DVD-ROM in the DVD-ROMdevice. The output of the light detecting element 107 is amplified, anoutput signal from the light detecting element 107 is selected accordingto the kind of the optical disk 102, and a tracking error signal (TE), afocus error signal (FE), a reproduction signal (RF), an All Sum signal(AS), an RF envelope signal (RFENV) and so on are generated based on theoutput signal, and the signals are outputted. Reference numeral 108denotes a converting unit which converts a reproduction signal outputtedfrom the reading unit 104 to digital data.

Reference numeral 109 denotes a radius direction driving unit whichdrives the reading unit 104 in the radius direction of the optical disk102. The radius direction driving unit 109 is constituted of, forexample, a traverse driving unit 110 which moves the whole reading unit104 in the radius direction of the optical disk and a tracking actuator111 which drives the object lens 106 in the reading unit 104 in theradius direction and finely drives the object lens 106 in the radiusdirection of the optical disk 102.

Reference numeral 112 denotes a track cross detecting unit whichgenerates a track cross pulse based on a reproduction signal when thelaser light of the reading unit 104 traverses tracks on the opticaldisk.

Reference numeral 113 denotes a track cross direction detecting unitwhich detects a direction when the laser light of the reading unit 104traverses the tracks on the optical disk. For example, the track crossdetecting unit 112 and the track cross direction detecting unit 113binarize a tracking error signal, which is outputted from the readingunit 104, by using a hysteresis comparator, a comparator, or the likeand generate a track count signal TKC. Further, a non-on-track signalOFTR is similarly generated from the envelope of an RF signal and atrack cross direction signal is generated based on a phase relationshipbetween TCK and OFTR signals. A method of directly using the TKC and amethod of latching the TKC by OFTR to generate a detected pulse, andother methods are available for a track cross detected pulse.

Reference numeral 114 denotes a rotational position information outputunit which detects the rotation angle of the disk rotating unit 103. Therotational position information output unit 114 generally uses a signalcalled an FG pulse which is generated from, for example, the output of aHall device of a disk motor. As to the FG signal, three pulses areoutputted for one rotation in a three-phase motor. Thus, a rotationangle can be detected in 60 degrees by counting both of a rising edgeand a falling edge. Moreover, other than the FG pulse, the followingmethod is available: a rotational speed detecting unit using an encoderis added to a disk motor and a rotational speed is detected with anarbitrary resolution.

Reference numeral 201 denotes a rotational position information dividingunit which further divides rotational position information, which isoutputted from the rotational position information output unit 114,evenly into m and outputs more detailed rotational position information.As a dividing method, the following is applicable: a method of dividingthe interval of the rotational position information into k and a methodof further dividing one-division time of the rotational positioninformation output unit 114 into k based on time for one rotation.

Reference numeral 115 denotes a counting unit which has a mode forcounting the number of track crossing times with a code indicating adirection based on the outputs of the track cross detecting unit 112 andthe track cross direction detecting unit 113 according to the output ofthe rotational position information dividing unit 201 and a mode forperforming counting without a code indicating a track cross direction.When rotational position information can be outputted every 60 degreesas described above, one rotation is divided into six×k areas and thenumber of track counts is counted with or without the code for each ofthe areas.

Reference numeral 116 denotes a control unit which receives signals fromthe converting unit 108 and the counting unit 115, processes thesignals, and controls the disk rotating unit 103, the reading unit 104,the converting unit 108, and the radius direction driving unit 109.

Subsequently, the following will describe the operation of the controlunit 116 which detects a vibration and sets the maximum rotationalspeed.

Referring to FIG. 6, the present embodiment will describe an example inwhich the DVD-ROM reproducing device 101 has corresponding reproducingspeeds of:

-   CD:    -   8×CAV (about 1660 rpm)    -   16×CAV (about 3330 rpm)    -   24×CAV (about 4990 rpm)-   DVD:    -   2.5×CAV (about 1430 rpm)    -   5×CAV (about 2870 rpm)    -   8×CAV (about 4590 rpm),        the output of the rotational position information output unit        114 has one rotation divided into six, and the rotational        position information dividing unit 201 has the number of        divisions k=2.

The control unit 116 controls the disk rotating unit 103 to make arotation at the first rotational speed. It is preferable that the firstrotational speed is a sufficiently low speed causing no vibration whenthe information disk 102 is rotated. For example, in the presentembodiment, measurements are performed at the first rotational speed ofCD 8×CAV (1660 rpm) and DVD 2.5×CAV (1430 rpm).

Then, the radius direction driving unit 109 is made nonoperational.Since track crossing is caused by an eccentric component between thetracks of the information disk 102 and the reading unit 104. Thus, foreach area obtained by dividing one rotation into 6×2=12, the countedvalue of the counting unit 115 is obtained with the code indicating atrack cross direction based on the output of the rotational positioninformation dividing unit 201.

Counted value data obtained at the first rotational speed is expressedby the equation below.DAT1[1]˜DAT1[1 2]  (Equation 38)

Further, measurements are performed at the second, third, . . . speedshigher than the first speed. The present embodiment will describe anexample of measurements only at the second rotational speed higher thanthe first rotational speed.

Also in the step of obtaining a counted value of the counting unit 115when a rotation is made at the second speed higher than the first speed,the counting results of the number of track crossing times can beobtained at a rotation angle of 30 degrees, which is obtained bydividing one rotation into twelve, as in the step of obtaining themeasurement results of the counting unit 115 when a rotation is made atthe first speed. In the present embodiment, a counted value is obtainedat a common rotational speed of 4000 rpm in order to decide whether ornot reproduction can be performed at the maximum speed (CD 24×CAV, DVD8×CAV) both on a DVD-ROM and a CD-ROM.

The control unit 116 controls the disk rotating unit 103 to make arotation at 4000 rpm. Similarly, the radius direction driving unit 109is made nonoperational. Then, track crossing is caused by an eccentriccomponent+a vibration component between the tracks of the informationdisk 102 and the reading unit 104. Thus, the counted value of thecounting unit 115 is obtained with the code indicating a track crossdirection based on the output of the rotational position informationoutput unit 114 for each of the areas obtained by dividing one rotationinto six. The obtained counted value is expressed by the equation below.DAT2[1]˜DAT2[12]  (Equation 39)

Therefore, track crossing caused by a vibration is obtained bysubtracting a counted value at the first rotational speed from a countedvalue at the second rotational speed (4000 rpm) at each correspondingrotational angle. FIG. 6 shows the relationship.

The data of each region is expressed by the equation below.DAT[1]=DAT2[1]−DAT1[1]DAT[2]=DAT2[2]−DAT1[2]DAT[3]=DAT2[3]−DAT1[3]DAT[4]=DAT2[4]−DAT1[4]DAT[5]=DAT2[5]−DAT1[5]DAT[6]=DAT2[6]−DAT1[6]DAT[7]=DAT2[7]−DAT1[7]DAT[8]=DAT2[8]−DAT1[8]DAT[9]=DAT2[9]−DAT1[9]DAT[10]=DAT2[10]−DAT1[10]DAT[11]=DAT2[11]−DAT1[11]DAT[12]=DAT2[12]−DAT1[12]  (Equation 40)Based on the data, vibration amplitude is approximated by the equationbelow. $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{12}{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 41} )\end{matrix}$By comparing a vibration detection value obtained by (equation 41) witha predetermined threshold value, it is decided whether or notreproduction should be performed at the maximum rotational speed.Additionally, a vibration quantity obtained by (equation 41) includes anerror relative to a precise vibration quantity. The error will bedescribed below.

If the counted values of DAT[1] to DAT[12] are counted without the codeindicating a track cross direction, no error occurs relative to theprecise vibration quantity. The sum of DAT[1] to DAT[12] serves as atotal number of traversed tracks for one rotation and one fourth of thesum serves as a vibration quantity. However, in order to measure aneccentric component in advance, measure eccentricity+a vibrationcomponent, calculate a difference between the measurement results, andacquire track cross data of the vibration component, it is necessary toprovide data having counted values which are counted with the codeindicating a track cross direction. As a matter of course, the countedvalue of the vibration component that serves as the difference also hasthe code.

Between the sum of absolute values of data having the code and the sumof absolute values of data not having the code, an error occurs on apart where the track cross direction is reversed. For example, as shownin FIG. 7(a), when areas obtained by dividing one rotation have aboundary coincident with the part where the track cross direction isreversed, regarding the counting results of the number of traversedtracks in DAT[a] and DAT[a+1] areas, absolute values are equal incounting with the code indicating the track cross direction and countingnot having the code.

However, as shown in FIG. 7(b), when areas obtained by dividing onerotation has a boundary in the DAT[a] area, in the case of countingwithout the code indicating the track cross direction, the sum oftraversed tracks before and after the reversal of the track crossdirection is counted. Meanwhile, when counting is performed with thecode, the code of the counting result of the traversed tracks is alsoreversed on the part where the track cross direction is reversed. Thus,the counting result of the area is a difference between counted valuesbefore and after the reversal of the track cross direction. As a matterof course, the difference between the counting results decreases as thenumber of divisions for one rotation increases and an area decreaseswhere the track cross direction is reversed.

As described above, according to Embodiment 2, the number of traversedtracks is counted for each of the k areas obtained by evenly dividingthe rotational position information of the rotational positioninformation detecting unit. Thus, it is possible to acquire moredetailed rotational position information for one rotation, increaseaccuracy, and calculate a vibration detection value proportionate tovibration amplitude without the necessity for complicated calculations.Hence, it is possible to promptly calculate a vibration detection valueand control a recording/reproducing speed without an extra number ofprogram steps.

Besides, the present embodiment described the DVD-ROM reproducing deviceas an example. The present embodiment can be similarly carried out in adisk recording/reproducing device such as a CD-ROM reproducing deviceand a CD-R/RW recording/reproducing device.

Further, the present embodiment described the example in which theinformation disk 102 is rotated at CAV (constant rotational speed)during reproduction. Even when the information disk 102 is controlled atCLV (constant linear velocity), ZCLV (constant linear velocity in eachzone), PCAV (combination of CLV and CAV), and so on during recording andreproduction, the present embodiment can be similarly carried out bydeciding whether control is performed so as to have a speed not reachingthe rotational speed for the similar vibration detection or a speedaround the rotational speed, or control is performed so as to rotate theinformation disk 102 to the maximum rotational speed.

Further, the present embodiment described the example in which therotational speed of the information disk 102 is controlled by measuringtrack crossing, caused by eccentricity+vibration, only at the secondrotational speed higher than the first rotational speed. The presentembodiment can be similarly carried out by performing measurements atone or more rotational speeds such as the second, third, . . . speedshigher than the first rotational speed and comparing a vibrationquantity with a threshold value having been prepared for each of therotational speeds.

Moreover, the present embodiment described the example in which thespindle motor serving as the disk rotating unit 103 have three poles,one rotation is divided into six areas and each area is further dividedinto two by using the rising edge and the falling edge of the FG pulse,and track crossing is measured for each of the areas obtained bydividing one rotation into 12. The present embodiment can be similarlycarried out when the spindle motor has four poles and one rotation isdivided into eight areas and when one rotation is divided into moreareas.

Embodiment 3

Referring to FIG. 8, the following will describe an information diskrecording/reproducing device and a method for controlling arecording/reproducing speed thereof according to Embodiment 3 of thepresent invention. A DVD-ROM reproducing device will be discussed as anexample.

FIG. 8 is an explanatory drawing showing an error calculating methodwhen a track cross direction is detected and a vibration quantity hasthe maximum error and the minimum error during the measurement of trackcrossing in the information disk recording/reproducing device accordingto Embodiment 3. A block diagram showing the configuration of theinformation disk recording/reproducing device according to Embodiment 3is identical to that of Embodiment 2. The explanation of the constituentelements performing the same operations is omitted.

Measurements are performed as the case where a total number of divisionsis m for one rotation. The track cross data of a vibration component foreach divided area is expressed by the equation below.DAT[1]˜DAT[m]  (Equation 42)Based on the data, vibration amplitude is approximated by the equationbelow. $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 43} )\end{matrix}$By comparing a vibration detection value obtained by (equation 43) witha predetermined threshold value, it is decided whether or notreproduction should be performed at the maximum rotational speed.

Additionally, a vibration quantity obtained by (equation 43) includes anerror relative to a precise vibration quantity. The error will bedescribed below.

As described in Embodiment 2, as the number of divisions increases forone rotation, a vibration quantity expressed by (equation 43) has asmaller calculated error. However, the number of divisions for onerotation of a rotational position information output unit 114 is limitedby hardware. The number of divisions is six or eight when an FG pulse isused.

Further, a sufficient number of divisions is acquired in effect by usinga rotational position information dividing unit 201 or attaching anencoder to a disk rotating unit 103. When the encoder is used, the costincreases. When the number of divisions is increased more thannecessary, a work memory for storing counted values is increased incapacity, considerably consuming a valuable hardware resource such as asignal processing IC. Thus, the use of the encoder is not preferable.For this reason, the number of divisions for one rotation needs to bedetermined so as to be minimum within a required error range.

If the counted values of DAT[1] to DAT[m] are counted without the codeindicating a track cross direction, no error occurs relative to aprecise vibration quantity. The sum of DAT[1] to DAT[12] serves as atotal number of traversed tracks for one rotation and one fourth of thesum serves as a vibration quantity. However, in order to measure aneccentric component in advance, measure eccentricity+a vibrationcomponent, calculate a difference between the measurement results, andacquire track cross data of the vibration component, it is necessary toprovide data having counted values which are counted with the codeindicating a track cross direction. As a matter of course, the countedvalue of the vibration component that serves as the difference also hasthe code.

Between the sum of absolute values of data having the code and the sumof absolute values of data not having the code, an error occurs on apart where the track cross direction is reversed. For example, as shownin FIG. 8(a), when areas obtained by dividing one rotation has aboundary coinciding with the part where the track cross direction isreversed, regarding the counting results of the number of traversedtracks in DAT[a] and DAT[a+1] areas, absolute values are equal incounting with the code indicating the track cross direction and incounting not having the code. When m is an even number, an error is 0 inan area including a part where a track cross direction is reversed, attwo points on a diagonal line.

However, as shown in FIG. 8(b), an error occurs when areas obtained bydividing one rotation has a boundary in DAT[a] area. When counting isperformed without a code indicating a track cross direction, the sum ofthe number of traversed tracks before and after the track crossdirection is reversed. Meanwhile, when counting is performed with thecode, the code of the counting result of the traversed tracks is alsoreversed on the part where the track cross direction is reversed. Thus,the counting result of the area is a difference between counted valuesbefore and after the track cross direction is reversed.

The maximum error occurs when the m division for one rotation is an evennumber and the counting result is 0 in an area of the part where thetrack cross direction is reversed. At this point, since the number ofdivisions for one rotation is m, as shown in FIG. 8(b), regarding thenumber of traversed tracks before and after the track cross direction isreversed in the area, absolute values are expressed by the equationbelow. $\begin{matrix}{A( {1 - {\cos\quad\frac{\pi}{m}}} )} & ( {{Equation}\quad 44} )\end{matrix}$

Therefore, regarding an error of the number of traversed tracks for onerotation, a maximum value d is expressed by the equation below.$\begin{matrix}{d = {4{A( {1 - {\cos\quad\frac{\pi}{m}}} )}}} & ( {{Equation}\quad 45} )\end{matrix}$A total number of traversed tracks for one rotation is expressed by theequation below. $\begin{matrix}\begin{matrix}{\begin{matrix}{{TORTAL}\quad{NUMBER}\quad{OF}} \\{{TRAVERSED}\quad{TRACKS}}\end{matrix} = {\int_{0}^{2\quad\pi}{A{{\cos( {\omega\quad t} )}}}}} \\{= {4A}}\end{matrix} & ( {{Equation}\quad 46} )\end{matrix}$Hence, a percentage of an error to the total number of traversed tracksis expressed by the equation below. $\begin{matrix}{\frac{d}{\begin{matrix}{{TOTAL}\quad{NUMBER}\quad{OF}} \\{{TRAVERSED}\quad{TRACKS}}\end{matrix}} = {1 - {\cos\quad\frac{\pi}{m}}}} & ( {{Equation}\quad 47} )\end{matrix}$Additionally, when m is an odd number, even in the case where thecounting result of the number of traversed-tracks is 0 in one area whilea direction is detected, the counting result of traversed tracks is not0 in the area on the diagonal line. Thus, an error is always smallerthan the value of (equation 47).

Based on the number of divisions for one rotation, an error of the totalnumber of traversed tracks or vibration amplitude for one rotation canbe expressed by (equation 47). Thus, in consideration of accuracyrequired to measure vibration amplitude, an error can be evaluated using(equation 47) to determine the number of divisions for one rotation. Forexample, when the rotational position information output unit 114 isconfigured using FG, the number of divisions for one rotation isgenerally six or eight (two times the number of poles of the magneticpole in the spindle motor) in this part.

When an error on the calculation of a vibration quantity is desired tobe set at 1% or less, the number of divisions in the rotational positioninformation dividing unit is set at four or three and the number ofdivisions for one rotation is set at 24. Hence, the vibration quantityhas an error of about 0.9% according to (equation 47). Even when arequired error is desired to be set at other value than this value, thepresent embodiment can be enabled similarly to this case by setting them divisions for one rotation so that an error value is calculated by(equation 47) based on the m divisions for one rotation to have an errorsmaller than the required error.

As described above, according to Embodiment 3, it is possible to keep anerror of a calculated vibration quantity value with required accuracywhile minimizing the number of divisions of the rotational positioninformation output unit. Thus, without the necessity for an extra numberof program steps, it is possible to promptly calculate a vibrationdetection value and control a recording/reproducing speed.

Besides, the present embodiment described the example of the DVD-ROMreproducing device. The present embodiment can be similarly carried outin a disk recording/reproducing device such as a CD-ROM reproducingdevice and a CD-R/RW recording/reproducing device.

1. An information disk recording/reproducing device, in which recordingor reproduction can be performed on an information disk having aninformation recording track formed like a spiral or a concentric circle,comprising: a disk rotating unit for rotating the information disk; arotational position information output unit for outputting rotationalposition information for the information disk of the disk rotating unitin each area provided by dividing one rotation into m (m is a naturalnumber equal to or larger than 2); a reading unit for reading aninformation signal from the information disk; a radius direction drivingunit for driving the reading unit in a radius direction of theinformation disk; a track cross detecting unit for detecting a trackcross caused by crossing and generating a track cross signal based on areproduction signal when the reading unit is traversed on theinformation recording track by the driving of the radius directiondriving unit; a track cross direction detecting unit for detecting adirection of the track crossing caused by the crossing based on thereproduction signal when the reading unit is traversed on theinformation recording track by the driving of the radius directiondriving unit; a counting unit for counting pulses of a track crosssignal from the track cross detecting unit, with a code indicating atrack cross direction from the track cross direction detecting unit,based on an output from the rotational position information output unitin each of the areas divided into m; and a control unit which rotatesthe disk rotating unit at a first speed, obtains a first counted valueof the counting unit while making the radius direction driving unitnonoperational, rotates the disk rotating unit at one or more kinds ofrotational speeds of second, third, . . . rotational speeds higher thanthe first rotational speed, obtains second, third, . . . counted valuesof the counting unit while making the radius direction driving unitnonoperational, and compares a difference between the first countedvalue and the second, third, . . . counted values with a predeterminedthreshold value so as to determine a maximum rotational speed of theinformation disk while using, as a vibration detection value, a valueproportionate to a sum of absolute values of counted values obtained inthe areas divided into m.
 2. An information disk recording/reproducingdevice, in which recording or reproduction can be performed on aninformation disk having an information recording track formed like aspiral or a concentric circle, comprising: a disk rotating unit forrotating the information disk; a rotational position information outputunit for outputting rotational position information for the informationdisk of the disk rotating unit in each area provided by dividing onerotation into n (n is a natural number equal to or larger than 2); arotational position information dividing unit which further divides intok (k is a natural number equal to or larger than 1) the area having beenprovided by dividing one rotation into n for the rotational positioninformation from the rotational position information output unit andoutputs the rotational position information in each of m=n·k areas; areading unit for reading an information signal from the informationdisk; a radius direction driving unit for driving the reading unit inthe radius direction of the information disk; a track cross detectingunit for detecting a track cross caused by crossing and generating atrack cross signal based on a reproduction signal when the reading unitis traversed on the information recording track by the driving of theradius direction driving unit; a track cross direction detecting unitfor detecting a direction of the track cross caused by the crossingbased on the reproduction signal when the reading unit is traversed onthe information recording track by the driving of the radius directiondriving unit; a counting unit for counting pulses of a track crosssignal from the track cross detecting unit, with a code indicating atrack cross direction from the track cross direction detecting unit,based on an output from the rotational position information dividingunit in each of the areas divided into m; and a control unit whichrotates the disk rotating unit at a first speed, obtains a first countedvalue of the counting unit while making the radius direction drivingunit nonoperational, rotates the disk rotating unit at one or more kindsof rotational speeds of second, third, . . . rotational speeds higherthan the first rotational speed, obtains second, third, . . . countedvalues of the counting unit while making the radius direction drivingunit nonoperational, and compares a difference between the first countedvalue and the second, third, . . . counted values with a predeterminedthreshold value so as to determine a maximum rotational speed of theinformation disk while using, as a vibration detection value, a valueproportionate to a sum of absolute values of counted values obtained inthe areas divided into m.
 3. The information disk recording/reproducingdevice according to claim 1, wherein in each of the areas divided intom, a difference between the counted value at the first rotational speedand the counted value at each of the second, third, . . . rotationalspeeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 1) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 2} )\end{matrix}$ and a value proportionate to the vibration quantity isused as a vibration detection value.
 4. The information diskrecording/reproducing device according to claim 1, wherein in each ofthe areas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 3) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}\quad{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x - 1}^{m}{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 4} )\end{matrix}$ a value proportionate to the vibration quantity is used asa vibration detection value, and the m divisions for one rotation isdetermined within a permissible error range based on a maximum value ofan error relative to an actual vibration quantity at this point, themaximum value being expressed by the equation below: $\begin{matrix}{{ERROR} \leq {1 - {\cos\frac{\pi}{m}}}} & ( {{Equation}\quad 5} )\end{matrix}$
 5. The information disk recording/reproducing deviceaccording to claim 1, wherein in each of the areas divided into m, adifference between the counted value at the first rotational speed andthe counted value at each of the second, third, . . . rotational speedsis expressed by the equation below:DAT[1]˜DAT[m]  (Equation 6) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}{\quad\quad}{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 7} )\end{matrix}$ a value proportionate to the vibration quantity is used asa vibration detection value, and the m divisions for one rotation is setat 24 so that an error relative to an actual vibration quantity at thispoint has a maximum value of 1% or less.
 6. A method for controlling arecording/reproducing speed of an information disk recording/reproducingdevice, in which recording or reproduction can be performed on aninformation disk having an information recording track formed like aspiral or a concentric circle, the device comprising a disk rotatingunit for rotating the information disk, a reading unit for reading aninformation signal from the information disk, and a radius directiondriving unit for driving the reading unit in a radius direction of theinformation disk, the method comprising the steps of: rotating theinformation disk; outputting rotational position information for theinformation disk in each area provided by dividing one rotation into m(m is a natural number equal to or larger than 2); reading aninformation signal from the information disk; driving the reading unitin the radius direction of the information disk; detecting a track crosscaused by crossing and generating a track cross signal based on areproduction signal when the reading unit is traversed on theinformation recording track by the driving of the radius directiondriving unit; detecting a direction of the track cross caused by thecrossing based on the reproduction signal when the reading unit istraversed on the information recording track by the driving of theradius direction driving unit; counting pulses of a track cross signal,with a code indicating the track cross direction, to obtain a firstcounted value in each of the areas provided by dividing one rotation ofthe rotational position information into m while rotating the diskrotating unit at a first speed and making the radius direction drivingunit nonoperational; counting pulses of the track cross signal, with thecode indicating the track cross direction, to obtain second, third,counted values in each of the areas provided by dividing one rotation ofthe rotational position information into m while rotating the diskrotating unit at one or more kinds of second, third, . . . speeds higherthan the first speed and making the radius direction driving unitnonoperational; and comparing a difference between the first countedvalue and the second, third, . . . counted values with a predeterminedthreshold value so as to determine a maximum rotational speed of theinformation disk while using, as a vibration detection value, a valueproportionate to a sum of absolute values of counted values obtained inthe areas divided into m.
 7. A method for controlling arecording/reproducing speed of an information disk recording/reproducingdevice, in which recording or reproduction can be performed on aninformation disk having an information recording track formed like aspiral or a concentric circle, the device comprising a disk rotatingunit for rotating the information disk, a reading unit for reading aninformation signal from the information disk, and a radius directiondriving unit for driving the reading unit in a radius direction of theinformation disk, the method comprising the steps of: rotating theinformation disk; outputting rotational position information for theinformation disk in each of m=n·k areas provided by further dividinginto k (k is a natural number equal to or larger than 1) an area havingbeen provided by dividing one rotation into m (m is a natural numberequal to or larger than 2); reading an information signal from theinformation disk; driving the reading unit in the radius direction ofthe information disk; detecting a track cross caused by crossing andgenerating a track cross signal based on a reproduction signal when thereading unit is traversed on the information recording track by thedriving of the radius direction driving unit; detecting a direction ofthe track cross caused by the crossing based on the reproduction signalwhen the reading unit is traversed on the information recording track bythe driving of the radius direction driving unit; counting pulses of thetrack cross signal, with a code indicating the track cross direction, toobtain a first counted value in each of the areas provided by dividingone rotation of the rotational position information into m whilerotating the disk rotating unit at a first speed and making the radiusdirection driving unit nonoperational; counting pulses of the trackcross signal, with the code indicating the track cross direction, toobtain second, third, counted values in each of the areas provided bydividing one rotation of the rotational position information into mwhile rotating the disk rotating unit at one or more kinds of second,third, . . . rotational speeds higher than the first rotational speedand making the radius direction driving unit nonoperational; andcomparing a difference between the first counted value and the second,third, . . . counted values with a predetermined threshold value so asto determine a maximum rotational speed of the information disk whileusing, as a vibration detection value, a value proportionate to a sum ofabsolute values of counted values obtained in the areas divided into m.8. The method for controlling a recording/reproducing speed of aninformation disk recording/reproducing device according claim 6, whereinin each of the areas divided into m, a difference between the countedvalue at the first rotational speed and the counted value at each of thesecond, third, . . . rotational speeds is expressed by the equationbelow:DAT[1]˜DAT[m]  (Equation 8) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}{\quad\quad}{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 9} )\end{matrix}$ and a value proportionate to the vibration quantity isused as a vibration detection value.
 9. The method for controlling arecording/reproducing speed of the information diskrecording/reproducing device according claim 6, wherein in each of theareas divided into m, a difference between the counted value at thefirst rotational speed and the counted value at each of the second,third, . . . rotational speeds is expressed by the equation below:DAT[1]˜DAT[m]  (Equation 10) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}{\quad\quad}{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 11} )\end{matrix}$ a value proportionate to the vibration quantity is used asa vibration detection value, and the m divisions for one rotation isdetermined within a permissible error range based on a maximum value ofan error relative to an actual vibration quantity at this point, themaximum value being expressed by the equation below: $\begin{matrix}{{ERROR} \leq {{- \cos}\frac{\pi}{m}}} & ( {{Equation}\quad 12} )\end{matrix}$
 10. The method for controlling a recording/reproducingspeed of the information disk recording/reproducing device accordingclaim 6, wherein in each of the areas divided into m, a differencebetween the counted value at the first rotational speed and the countedvalue at each of the second, third, . . . rotational speeds is expressedby the equation below:DAT[1]˜DAT[m]  (Equation 13) a vibration quantity at this point isapproximated by the equation below: $\begin{matrix}{{{VIBRATION}{\quad\quad}{QUANTITY}} = {\frac{1}{4}{\sum\limits_{x = 1}^{m}\quad{{{DAT}\lbrack x\rbrack}}}}} & ( {{Equation}\quad 14} )\end{matrix}$ a value proportionate to the vibration quantity is used asa vibration detection value, and the m divisions for one rotation is setat 24 so that an error relative to an actual vibration quantity at thispoint has a maximum value of 1% or less.